1. Field of the Invention
The present invention relates to a display device, and more particularly, to a display device using a single liquid crystal display panel, by which a reduction in luminance is minimized using a single liquid crystal device.
2. Description of the Related Art
Existing types of display devices that are driven in a digital system include plasma display panels (PDP), liquid crystal display (LCD) panels and ferroelectric liquid crystal (FLC) panels.
FLC panels have a structure in which ferroelectric liquid crystal is sandwiched between an optical planar mirror formed on a silicon substrate and glass, and have a wide viewing angle and a fast response speed compared to existing panels.
A display device using a single LCD panel according to the art related to the present invention is made up of a signal processing unit, a timing control unit, an optical engine and a screen. The optical engine is made up of a color switch, an FLC panel, and an optical system having an optical source, a collimating lens, a polarized beam splitter and a projection lens.
The signal processing unit receives R (red), G (green) and B (blue) signals, controls the offset, contrast and brightness of the received signals, performs signal processing such as gamma correction, and then generates R, G, and B data in synchronization with a vertical synchronization signal on a field-by-field basis to display R, G, and B data on the LCD panel. The timing control unit receives a vertical synchronization signal and a horizontal synchronization signal, and generates a color switching control signal for controlling the color switch. In the optical engine, light emitted from the optical source is split into R, G, and B light beams. The R, G, and B light beams are sequentially transmitted using the color switch, the transmitted R, G, and B light beams are transmitted or reflected by the LCD panel according to the R, G, and B data, and then the light beams are displayed on the screen via the optical system.
In order to display colors using a single LCD panel, in the art, R, G, and B colors time-share one vertical period, and each is displayed for one third of a vertical period. As shown in FIG. 2, the quantity of light of each of the R, G, and B light beams is ⅓, and the output time of light of each of the R, G, and B light beams is also ⅓, so that the maximum luminance, which is the sum of the products of the quantity of each light by the output time of each light, is ⅓.
The maximum brightness in the art related to the present invention is just about ⅓ of the maximum brightness when three LCD panels are used to display R, G, and B colors, respectively. Therefore, a screen appears dark due to a reduction in luminance.
Exemplars of the art are U.S. Pat. No. 6,122,028 issued to Gilmour et al. for REFLECTIVE LIQUID CRYSTAL DEVICE WITH POLARIZING BEAM SPLITTER, U.S. Pat. No. 6,104,446 issued to Blankenbecler et al. for COLOR SEPARATION OPTICAL PLATE FOR USES WITH LCD PANELS, U.S. Pat. No. 6,025,885 issued to Deter for PROCESS FOR COLOR TRANSFORMATION AND A COLOR VIDEO SYSTEM, U.S. Pat. No. 5,929,843 issued to Tanioka for IMAGE PROCESSING APPARATUS WHICH EXTRACTS WHITE COMPONENT DATA, U.S. Pat. No. 5,884,991 issued to Levis et al. for LCD PROJECTION SYSTEM WITH POLARIZATION DOUBLER, U.S. Pat. No. 5,781,265 issue to Lee for NON-CHIRAL SMECTIC C LIQUID CRYSTAL DISPLAY, U.S. Pat. No. 5,512,948 issued to Iwamatsu for NEGATIVE-IMAGE SIGNAL PROCESSING APPARATUS, U.S. Pat. No. 5,309,170 issued to Takashi et al. for HALF-TONE REPRESENTATION SYSTEM AND CONTROLLING APPARATUS, U.S. Pat. No. 4,574,636 issued to Satake for APPARATUS FOR EXAMINING AN OBJECT BY USING ULTRASONIC BEAMS, JP10123477 issued to Yoneda et al. for LIQUID CRYSTAL PROJECTOR, JP10023445 issued to Semasa for PICTURE DISPLAY DEVICE, JP 8294138 issued to Ozuru et al. for LIQUID CRYSTAL PROJECTOR, JP 10148885 (EP 0843487) issued to Endo et al. for PROJECTOR APPARATUS, JP 9090402 issued to Takigawa et al. for PICTURE DISPLAY DEVICE, JP 11006980 issued to Miyashita for PROJECTION DEVICE, and JP 8168039 issued to Nomura et al. for PROJECTION DISPLAY SYSTEM AND PROJECTION POSITION ADJUSTING METHOD. I have found that the art does not teach a display device having a single liquid crystal display that has the image quality and luminance of the present invention.
To solve the above problem, an objective of the present invention is to provide a display device adopting a single liquid crystal display (LCD) panel, by which a reduction in luminance is improved to half the luminance when three LCD panels are used, although just one LCD panel is used.
It is another object to have a single ferroelectric liquid crystal panel, by which a reduction in luminance is improved over multiple ferroelectric liquid crystal panels.
It is yet another object to have an algorithm for converting R/G/B signal to a R/G/B/W(white) signal that allows for improved luminance.
It is still yet another object to increase luminance by adding an achromatic color to an input signal of image projecting device.
To achieve the above objectives, the present invention provides a display device using a single LCD panel, the device includes a format conversion unit for receiving signals Ri, Gi and Bi corresponding to one vertical period and generating signals Ro, Go, Bo and W (white), which have been compensated for in a loss in color saturation using a display panel control signal and a predetermined arithmetic algorithm, at intervals of one vertical period; and an optical engine for sequentially outputting four color signals to a screen in accordance with the signals Ro, Go, Bo and W output from the format conversion unit, under the control of the display panel control signal.